a) Field of the Invention
The present invention relates to a winding device suitable for winding media such as roll papers output by a large-scale printer. More specifically, the present invention relates to a winding device equipped with a looseness-detecting sensor for detecting the looseness of the output media.
b) Description of the Prior Art
Normally used as drawing media for large-scale full color printers (of ink jet or electrostatic recording types) are papers, films, or cloths which are wound around a pipe-like paper tube made of cardboard. In particular, the medium printed in high resolution is a high value added product, so extra careful handling is required for storing the medium after printing.
One of the means for storing the medium after printing is, as illustrated in FIGS. 26 and 27, a method for winding a printed medium 100 on a paper tube 102 using a winding device 101 to store the wound-up medium 100 in a roll. This method is suitable when a laminate treatment is provided in a following process because the roll medium 100, rather than cut sheets, can be processed continuously.
In such a winding device 101, the paper tube 102 as a winding core is held on both sides and secured by flanges 103, and a front edge of the medium 100 printed by a printer 104 is attached to the paper tube 102 with scotch-type tape. Here, a cylindrical roller weight 106 is used to tension the medium 100 from a paper outlet 105 of the printer 104 to the flange 103, and a medium guide 107 is provided to prevent interference between the medium 100 and the printer 104.
If the medium 100 becomes loose by more than a predetermined amount as the printer 104 keeps printing out the medium 100, the weight 106 is lowered so that the loose condition is optically detected by a looseness-detecting sensor 108 and the winding flange 103 is driven to wind the medium 100. When the amount of looseness decreases to a predetermined level, the tensioned condition of the medium 100 is detected by the looseness-detecting sensor 108 and the flange 103 stops rotating. Thus, the continuous roll medium 100 is wound by intermittent rotations of the flange 103.
However, since the above mentioned winding device 101 uses the optical looseness-detecting sensor 108, when light-emitting and light-receiving portions of the sensor 108 are contaminated, when a scotch-type tape for attaching the medium 100 on the paper tube 102 is attached on the light-emitting portion or light-receiving portion of the sensor 108 due to careless handling by an operator, or when something is placed between the light-emitting portion and the light-receiving portion of the sensor 108, the looseness of the medium 100 cannot be detected. Consequently the medium 3 cannot be wound.
It is also difficult to adjust the optical axis of the sensor 108 when the light-emitting portion and light-receiving portion of the looseness-detecting sensor 108 are used in the printer 104; even after successful mounting of those elements in the printer, operators may hit the printer and the optical axis of the sensor 108 is shifted. Thus, the accurate positioning of the optical axis of the sensor 108 cannot be guaranteed. For this reason, the detection of the looseness of the medium is not reliable. Further, a wire 109, which connects the light-emitting portion and light-receiving portion of the looseness-detecting sensor 108 and a driving motor of the flange 103, extends over the entire width of the medium 100. Wiring is a complicated operation.
When the printed medium 100 is cut in size of A0, A1, A2, etc., it is necessary to equip a sheet tray 110 for receiving the cut medium 100. However, the medium guide 107 needs to be removed to use the sheet tray 110. Every time the sheet tray 110 is attached/detached, the medium guide 107 also needs to be detached/attached, requiring frequent operations and complicated management of the components.
There is a winding device 101 that does not use the weight 106 and medium guide 107 for winding the medium 100 on the paper tube 102. However, such a conventional winding device 101 is not designed to be used with the sheet tray 110. If the sheet tray 110 is used with the winding device 101 attached, the medium 100 is jammed at the winding device 101. Thus, each time the sheet tray 110 is used, the winding device 101 needs to be removed.
Then, a primary object of the present invention is to provide a winding device which does not need to be removed even when the sheet tray is used.
To achieve this object, in a winding device comprising a winding mechanism, which winds a thin medium such as paper, film, or cloth output by a printer on a winding core, and a looseness-detecting sensor, which detects looseness of the medium and actuates the winding mechanism upon the detection, the present invention is characterized by the fact that the looseness-detecting sensor is capable of receding from the moving area of the medium when a sheet tray is attached to the printer.
Thus, when the sheet tray is attached for stocking up the cut medium after printing, the looseness-detecting sensor can be caused to recede from the moving area of the medium. Consequently, the medium is prevented from intruding on the looseness-detecting sensor. Accordingly, there is no need to detach/attach a whole or part of the winding device when the sheet tray is attached/detached. This improves usability and eliminates the management of the components with the exception of the sheet tray.
The invention is further characterized by the fact that, in the winding device as discussed above, the looseness-detecting sensor is a mechanical contact-type sensor that performs detection as the medium comes into contact therewith and is integrated with the winding mechanism.
Since the sensor is of a contact-type, detection is kept accurate while it may be degraded in an optical sensor because the optical axis of the sensor is transgressed intercepted due to contamination or shifted after installation. Thus, reliability of detection can be improved. Because the looseness-detecting sensor is integrated with the winding mechanism, there is no need to wire the sensor with the winding mechanism, which is normally required when the optical sensor is used in the printer. This simplifies the operation of mounting the sensor in the printer. Since a contact-type sensor is generally less expensive than an optical sensor, the cost of components is reduced.
Further, the invention is characterized by the fact that, in the winding device set forth above, a contact lever of the looseness-detecting sensor, with which the medium makes contact, is capable of swinging with a very small force. Therefore, the contact lever is protected from bending or damage when the medium comes into contact therewith.